bpf: don't bother with getname/kern_path - use user_path_at

kernel/bpf/inode.c misuses kern_path...() - it's much simpler (and
more efficient, on top of that) to use user_path...() counterparts
rather than bothering with doing getname() manually.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200120232858.GF8904@ZenIV.linux.org.uk

diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c
index ecf42bec38c001178563e11feab3ded018e0a312..e11059b99f1883b1f509dfbf96e68f644436fb58 100644 (file)
--- a/kernel/bpf/inode.c
+++ b/kernel/bpf/inode.c
@@ -380,7 +380,7 @@ static const struct inode_operations bpf_dir_iops = {
        .unlink         = simple_unlink,
 };
 
-static int bpf_obj_do_pin(const struct filename *pathname, void *raw,
+static int bpf_obj_do_pin(const char __user *pathname, void *raw,
                          enum bpf_type type)
 {
        struct dentry *dentry;
@@ -389,7 +389,7 @@ static int bpf_obj_do_pin(const struct filename *pathname, void *raw,
        umode_t mode;
        int ret;
 
-       dentry = kern_path_create(AT_FDCWD, pathname->name, &path, 0);
+       dentry = user_path_create(AT_FDCWD, pathname, &path, 0);
        if (IS_ERR(dentry))
                return PTR_ERR(dentry);
 
@@ -422,30 +422,22 @@ out:
 
 int bpf_obj_pin_user(u32 ufd, const char __user *pathname)
 {
-       struct filename *pname;
        enum bpf_type type;
        void *raw;
        int ret;
 
-       pname = getname(pathname);
-       if (IS_ERR(pname))
-               return PTR_ERR(pname);
-
        raw = bpf_fd_probe_obj(ufd, &type);
-       if (IS_ERR(raw)) {
-               ret = PTR_ERR(raw);
-               goto out;
-       }
+       if (IS_ERR(raw))
+               return PTR_ERR(raw);
 
-       ret = bpf_obj_do_pin(pname, raw, type);
+       ret = bpf_obj_do_pin(pathname, raw, type);
        if (ret != 0)
                bpf_any_put(raw, type);
-out:
-       putname(pname);
+
        return ret;
 }
 
-static void *bpf_obj_do_get(const struct filename *pathname,
+static void *bpf_obj_do_get(const char __user *pathname,
                            enum bpf_type *type, int flags)
 {
        struct inode *inode;
@@ -453,7 +445,7 @@ static void *bpf_obj_do_get(const struct filename *pathname,
        void *raw;
        int ret;
 
-       ret = kern_path(pathname->name, LOOKUP_FOLLOW, &path);
+       ret = user_path_at(AT_FDCWD, pathname, LOOKUP_FOLLOW, &path);
        if (ret)
                return ERR_PTR(ret);
 
@@ -480,36 +472,27 @@ out:
 int bpf_obj_get_user(const char __user *pathname, int flags)
 {
        enum bpf_type type = BPF_TYPE_UNSPEC;
-       struct filename *pname;
-       int ret = -ENOENT;
        int f_flags;
        void *raw;
+       int ret;
 
        f_flags = bpf_get_file_flag(flags);
        if (f_flags < 0)
                return f_flags;
 
-       pname = getname(pathname);
-       if (IS_ERR(pname))
-               return PTR_ERR(pname);
-
-       raw = bpf_obj_do_get(pname, &type, f_flags);
-       if (IS_ERR(raw)) {
-               ret = PTR_ERR(raw);
-               goto out;
-       }
+       raw = bpf_obj_do_get(pathname, &type, f_flags);
+       if (IS_ERR(raw))
+               return PTR_ERR(raw);
 
        if (type == BPF_TYPE_PROG)
                ret = bpf_prog_new_fd(raw);
        else if (type == BPF_TYPE_MAP)
                ret = bpf_map_new_fd(raw, f_flags);
        else
-               goto out;
+               return -ENOENT;
 
        if (ret < 0)
                bpf_any_put(raw, type);
-out:
-       putname(pname);
        return ret;
 }